Login into the remote administration of your router then look for the wireless security part. Enable WPA-PSK or WPA2 encryption and make a password of completely random characters and numbers with a length of 63 for your password. Also change the default password on your router. A good idea to get maximum distance is to change your signal channel to either 1 or 11 instead of 6. Do not disable SSID broadcast or enable MAC filtering. Worthless precautions that only cause connectivity issues.
Wireless Data and Voice Communications Security Solutions